SYNERGISM OF THIDIAZURON AND BENZYLADENINE IN AXILLARY SHOOT FORMATION DEPENDS ON SEQUENCE OF APPLICATION IN MISCANTHUS X OGIFORMIS GIGANTEUS

Shoots of Miscanthus X ogiformis Honda 'Giganteus' transferred from me dium with benzyladenine (BA) to thidiazuron (TDZ) formed significantly more axillary shoots than shoots grown continuously on either medium, or transferred from TDZ to BA. Shoot formation on axillary shoots tra nsferred from BA-containing media to media with kinetin or isopentenyl adenine (2iP) or transferred from media with TDZ, kinetin or 2iP to me dia with BA, corresponded to the number of shoots formed in the previo us subculture. Shoot formation on shoots transferred from medium conta ining BA to media containing combinations of BA and/or TDZ increased w ith increasing concentrations of TDZ in the first subculture, whereas shoot formation in the second and third subculture depended on the BA concentration. When shoots were transferred from media with BA to medi a with TDZ, the time for shoot formation, as well as shoot size, indic ate that the combined effect of BA and TDZ is expressed only during th e early phase of the subculture. The results suggest that adenine- and phenylurea-type cytokinins have a common binding site in the plant ce ll, and a model is proposed.